1. Field of the Invention
The invention relates to an electronic apparatus; more particularly, the invention relates to a sensing apparatus of a display panel.
2. Description of Related Art
FIG. 1 is a block diagram illustrating circuitry of a conventional active matrix organic light emitting diode (AMOLED) display. The AMOLED display includes a gate driver 110, a source driver 120, and a display panel 130. The display panel 130 has a plurality of scan lines (for instance, scan lines S_1 and S_2 which are gate lines), a plurality of data lines (for instance, data lines D_1 and D_2 which are source lines), and a plurality of pixel circuits (e.g., a pixel circuit 131). The pixel circuit 131 has a switch 132, a current source transistor 133, and an organic light emitting diode (OLED) 134.
The gate driver 110 can sequentially scan the different scan lines of the display panel 130, so as to allow the source driver 120 to write the data voltage into the pixel circuit. As shown in FIG. 1, in the exemplary pixel circuit 131, while the gate driver 110 turns on the switch 132 via the scan line S_1, the source driver 120 can transmit the data voltage to the gate of the current source transistor 133 via the data line D_1 and the switch 132. The gate voltage of the current source transistor 133 may determine the current I1 of the current source transistor 133. The current I1 flowing through the OLED 134 may determine the brightness of the OLED 134. The formula expressing the relation between the gate source voltage VGS of the current source transistor 133 and the current I1 is I1=k(VGS−Vt)2, wherein the coefficient k is a real number, and Vt represents a threshold voltage of the current source transistor 133. Due to process drift or other factors, the threshold voltages of the current source transistors in different pixel circuits may differ from one another. The difference in the threshold voltages or the drift may lead to mura effects on images or other defects. If the threshold voltage of the current source transistor 133 may be measured, the source driver 120 is able to correspondingly adjust the data voltage to be written into the pixel circuit 131, so as to compensate the drift of the threshold voltage.